U.S. patent number 8,313,804 [Application Number 13/109,533] was granted by the patent office on 2012-11-20 for apparatus and methods for chemical vapor deposition.
This patent grant is currently assigned to Applied Materials, Inc.. Invention is credited to David K. Carlson, Satheesh Kuppurao, Errol Sanchez.
United States Patent |
8,313,804 |
Carlson , et al. |
November 20, 2012 |
Apparatus and methods for chemical vapor deposition
Abstract
Methods and apparatus are disclosed for the formation of
vaporizing liquid precursor materials. The methods or apparatus can
be used as part of a chemical vapor deposition apparatus or system,
for example for forming films on substrates. The methods and
apparatus involve providing a vessel for containing a liquid
precursor and diffusing element having external cross-section
dimensions substantially equal to the internal cross-sectional
dimensions of the vessel.
Inventors: |
Carlson; David K. (San Jose,
CA), Sanchez; Errol (Tracy, CA), Kuppurao; Satheesh
(San Jose, CA) |
Assignee: |
Applied Materials, Inc. (Santa
Clara, CA)
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Family
ID: |
38229865 |
Appl.
No.: |
13/109,533 |
Filed: |
May 17, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110217466 A1 |
Sep 8, 2011 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11697937 |
Apr 9, 2007 |
7967911 |
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60791230 |
Apr 11, 2006 |
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Current U.S.
Class: |
427/248.1;
427/497; 427/237 |
Current CPC
Class: |
C23C
16/4482 (20130101) |
Current International
Class: |
C23C
16/44 (20060101); C23C 16/448 (20060101); C23C
16/38 (20060101); C23C 16/30 (20060101) |
Field of
Search: |
;427/237,248.1,497 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1548813 |
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Jun 2005 |
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EP |
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60-131973 |
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Jul 1985 |
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JP |
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11-006065 |
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Jan 1999 |
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JP |
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2001115263 |
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Apr 2001 |
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JP |
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Other References
IPRP, PCT/US2007/066366 Oct. 14, 2008, 10 pp. cited by other .
PCT International Search Report, Nov. 4, 2007. cited by other .
Timmons, M. "A Study of cylinder design for solid OMVPE sources",
Journal of Crystal Growth, Elsevier vol. 221, No. 1-4 (200-12)
Amsterdam, NL Dec. 2000, 635-639. cited by other.
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Primary Examiner: Zervigon; Rudy
Attorney, Agent or Firm: Diehl Servilla LLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser.
No. 11/697,937, filed on Apr. 9, 2007 which claims priority under
35 U.S.C. 119(e) to U.S. Provisional Application No. 60/791,230,
filed Apr. 11, 2006.
Claims
What is claimed is:
1. A chemical vapor deposition method comprising: flowing a carrier
gas through a gas inlet conduit to a bottom portion of a vessel
defined by a wall and a bottom surface of the vessel, the vessel
including the porous sintered metal frit extending between the wall
of the vessel and defining a plenum in a bottom portion of the
vessel, the gas inlet conduit passing through the porous sintered
metal frit but not into the bottom portion of the vessel, the
porous sintered metal frit being submerged in a liquid reactant
contained between the wall of the vessel, causing the carrier gas
and the liquid reactant to flow through the porous sintered metal
frit to create a vapor from the liquid reactant; and transporting
the vapor to a chamber under conditions such that the liquid
reactant forms a layer on a substrate contained within the
chamber.
2. The method of claim 1, wherein the porous sintered metal frit
comprises includes stainless steel.
3. The method of claim 1, wherein the porous sintered metal frit is
separated from the bottom of the vessel by less than about 2
mm.
4. The method of claim 1, wherein the porous sintered metal frit
has a diameter of about 5.75 inches and a thickness of about 0.078
inches.
5. The method of claim 1, wherein the porous sintered metal frit
has a pore size of about 40 microns.
6. The method of claim 1, wherein the liquid reactant is absorbed
into pores and microchannels of the porous sintered metal frit.
7. A method of processing a substrate, the method comprising:
flowing a carrier gas through an inlet conduit to a liquid reactant
containing vessel; flowing the carrier gas and liquid reactant
through a porous sintered metal frit creating a vapor from the
liquid reactant; and flowing the vapor through an outlet conduit;
wherein the porous sintered metal frit is immersed in the liquid
reactant and positioned less than about 2 mm from a bottom of the
vessel.
8. The method of claim 7, further comprising flowing the vapor to a
processing chamber.
9. The method of claim 8, further comprising reacting the vapor
with a substrate in the processing chamber to form a layer on the
substrate.
10. The method of claim 7, wherein the porous sintered metal frit
comprises stainless steel.
11. The method of claim 7, wherein the porous sintered metal frit
has a diameter of about 5.75 inches and a thickness of about 0.078
inches.
12. The method of claim 7, wherein the porous sintered metal frit
has a pore size of about 40 microns.
13. A deposition method comprising: flowing a carrier gas into a
liquid reactant containing vessel having walls and a bottom
surface; flowing the carrier gas and liquid reactant through a
porous sintered metal frit extending between the walls of the
vessel and defining a plenum in a bottom portion of the vessel,
causing the carrier gas and the liquid reactant to flow through the
porous sintered metal frit to create a vapor comprising the liquid
reactant; and transporting the vapor to a chamber under conditions
such that the liquid reactant forms a layer on a substrate
contained within the chamber; wherein the porous sintered metal
frit is separated from the bottom of the vessel by less than about
2 mm.
14. The method of claim 13, wherein the porous sintered metal frit
is submerged in the liquid reactant.
15. The method of claim 13, wherein the porous sintered metal frit
comprises includes stainless steel.
16. The method of claim 13, wherein the porous sintered metal frit
has a diameter of about 5.75 inches and a thickness of about 0.078
inches.
17. The method of claim 13, wherein the porous sintered metal frit
has a pore size of about 40 microns.
18. The method of claim 13, wherein the liquid reactant is absorbed
into pores and microchannels of the porous sintered metal frit.
Description
BACKGROUND
Embodiments of the present invention pertain generally to apparatus
and methods for vaporizing and mixing a vaporized liquid with a
carrier gas. Embodiments of the invention are particularly suited
for supplying vaporized reactants to the reaction chamber of a
chemical vapor deposition system, for example, in semiconductor
device manufacturing equipment.
Chemical vapor deposition (CVD) processes are widely used in the
deposition of thin films used in semiconductor devices and
integrated circuits. Such processes involve deposition resulting
from a reaction of chemical vapors homogeneously or heterogeneously
on a substrate. The reaction rate is controlled by one or more
parameters, such as temperature, pressure and reactant gas flow
rates. The use of low vapor pressure liquids as precursors for such
processes has several advantages and has become more common.
Prior CVD processes involve transport of low vapor pressure liquid
using a bubbler or boiler. In these processes, a carrier gas
saturates the liquid and transports the vapor. Various liquid
reactants and precursors are used in CVD applications by delivering
the liquid reactants in a carrier gas. In liquid reactant CVD
systems, the carrier gas is typically bubbled at a controlled rate
through a container of the liquid reactant so as to saturate the
carrier gas with liquid reactant and the saturated carrier is then
transported to the reaction chamber.
Attempts have been made to deliver solid reactants to a CVD
reaction chamber, but with much less success. The delivery of solid
precursors in CVD processing is carried out using the
sublimator/bubbler method in which the precursor is usually placed
in a sublimator/bubbler reservoir which is then heated to the
sublimation temperature of the precursor to transform it into a
gaseous compound which is transported into the CVD reactor with a
carrier gas such as hydrogen, helium, argon, or nitrogen. However,
this procedure has been unsuccessful in reliably and reproducibly
delivering solid precursor to the reaction chamber for a number of
reasons. The major problems with the technique are centered on the
inability to consistently vaporize a solid at a controlled rate
such that a reproducible flow of vaporized solid precursor can be
delivered to the process chamber. Also, it is difficult to ensure
complete saturation of the fast flowing carrier gas stream because
of a limited amount of exposed surface area of the solid precursor
in the vaporizer system and lack of uniform temperature to provide
maximum sublimation. Although solid precursor sublimator/bubbler
systems and liquid precursor bubbler systems are both used for the
delivery of CVD reactants, each of these systems has different
problems and considerations. Therefore, a system or apparatus used
for a solid sublimator/bubbler will not necessarily work for a
liquid precursor bubbler apparatus.
Prior art apparatus for delivering the vapor formed by bubbling a
carrier gas through a liquid precursor are shown in FIGS. 1A and
1B. FIG. 1A shows a prior art vaporizer apparatus 10 including an
ampoule or vessel 12 containing a liquid precursor material 11. Gas
inlet tube 14 is connected to a source of carrier gas 30. Gas inlet
tube 14 extends beneath the level of liquid 11. Pressurized
delivery of carrier gas 30 provides a mixture 32 of vaporized
liquid precursor and carrier gas which then exits the vessel 12
through outlet conduit 16, which is connected to a CVD system (not
shown).
The diffuser material 20 is typically a porous, sintered metal, and
improves the bubbling efficiency of the vaporizer apparatus 10. The
vaporizers shown in FIGS. 1A and 1B deliver vapor from material in
a liquid state to a process chamber by heating the liquid material
in a container and introducing the carrier gas at a controlled rate
into the liquid material near the bottom of the container. The
carrier gas then becomes saturated with vapor from the liquid
material as the carrier gas bubbles to the top of the container.
The saturated carrier gas is then transported to the process
chamber, for example, a CVD apparatus used in semiconductor
manufacture.
In the apparatus shown in FIGS. 1A and 1B, bubbles of carrier gas
produce undesirable small droplets of the liquid precursor, which
may be referred to as microdroplets. The microdroplets are carried
together with the mixture of carrier gas and precursor vapor into
the outlet tube and to the process chamber. Such microdroplets can
cause defects in the finished products.
A need therefore remains for liquid vaporizer methods and apparatus
which can vaporize liquid at flow rates sufficient for CVD
processes and that reduce or prevent the delivery of small droplets
of liquid to the process chamber.
SUMMARY
Embodiments of the invention relate to apparatus and methods of
processing a wafer during a film-forming process in a reaction
chamber. According to a first embodiment, a chemical vapor
deposition apparatus comprises a chemical vapor deposition chamber
having a gas inlet port and a liquid reactant vaporizer. The liquid
reactant vaporizer has an outlet port connected to the chamber
inlet port. The vaporizer comprises a vessel including an upper
portion, a lower portion, interior lateral surfaces and a bottom
surface. According to the first embodiment, the vessel contains a
liquid reactant, and the space between the interior lateral
surfaces defines an interior vessel diameter. The apparatus further
includes an inlet port connected to a source of carrier gas, a
porous member having external diameter that is substantially equal
to the interior diameter of the vessel inserted into the lower
portion of the vessel below the level of the liquid reactant and
defining a plenum between the porous member and the bottom of the
vessel, and a gas delivery conduit extending through the gas inlet
port and the porous member.
The plenum is defined by a gap between the porous member and the
bottom of the vessel. In certain embodiments, the porous member is
in the shape of a disk. According to some embodiments, the disk is
composed of sintered metal, for example, a sintered metal frit,
such as a stainless steel frit. In one or more embodiments, the
apparatus is adapted for the formation of films on substrates.
Another embodiment pertains to a chemical vapor deposition
apparatus comprising a chemical vapor deposition reaction chamber
and a vaporizer. The vaporizer includes a closed substantially
cylindrical ampoule having a top portion, a bottom portion, a
bottom surface and an interior diameter bound by interior walls,
inlet and outlet ports extending from the top portion, the outlet
port in fluid communication with the reaction chamber and the inlet
port in fluid communication with a gas source. The vaporizer
further includes a porous plate having edge surfaces in contact
with the interior walls of the ampoule adjacent the bottom surface
and submerged in liquid reactant, the porous plate being mounted to
provide a space between the plate and the bottom surface and a gas
conduit extending from the inlet and through the porous plate. In
certain embodiments, the space between the plate and the bottom
surface is at least about 2 mm.
Still another embodiment of the invention pertains to a chemical
vapor deposition method comprising flowing a carrier gas through a
liquid reactant contained in a vessel defined by walls and a bottom
surface, the vessel including a porous member extending between the
walls of the vessel and defining a plenum in a bottom portion of
the vessel, the porous member submerged in the liquid reactant,
causing the carrier gas and the liquid reactant to flow through the
porous member to create a vapor from the liquid and transporting
the vapor to a chamber under conditions to convert the liquid
reactant to form a layer on a substrate contained within the
chamber. In one or more embodiments, the porous member comprises a
sintered frit, for example, a sintered metal frit, such as a
sintered stainless steel frit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A shows a prior art vaporizer apparatus;
FIG. 1B shows a prior art vaporizer apparatus; and
FIG. 2 shows an embodiment of a vaporizer apparatus according to
the present invention.
DETAILED DESCRIPTION
Before describing exemplary embodiments of the invention, it is to
be understood that the invention is not limited to the details of
construction or process steps set forth in the following
description. The invention is capable of other embodiments and of
being practiced or being carried out in various ways. Aspects of
the present invention provide methods and apparatus for chemical
vapor deposition, which may be used, for example, for forming thin
films on a substrate.
Referring to FIG. 2, an exemplary chemical vapor deposition
apparatus 210 is shown. CVD apparatus 210 includes an ampoule or
vessel 212 containing a liquid reactant or precursor 211. The
ampoule or vessel 212 may be cylindrical or any other suitable
shape. As shown in FIG. 2, vessel 212 is a closed vessel bounded by
interior walls 218 and bottom surface 222. The liquid reactant 211
is contained within a bottom portion of the vessel 212. Non
limiting examples of liquid reactants include such as TEOS,
trimethyl borate, tetraethyl borate, tetraethyl phosphate,
tetraethyl phosphite, tetrakis(dimethylamino)titanium diethyl
analog, water or the like is delivered from a liquid bulk delivery
tank. Gas inlet conduit 214 provides an inlet port which is
connected to a source 250 of carrier gas 230. The carrier gas may
be stored in pressurized containers and the flow of the gas may be
controlled by flow regulators and/or mass flow controllers as is
known in the art.
A diffuser element 232, which may be in the form of a plate or a
disk is inserted in the vessel 212 and extends between interior
walls 218 and adjacent bottom surface 222. The distance "D" between
the diffuser element 232 and bottom surface 222 according to one or
more embodiments is less than about 2 mm. The outer diameter or
other cross-sectional dimension of the diffuser element 232 is
substantially equal to the inner diameter or other cross-sectional
dimension of the vessel 212. As such, the diffuser element 232 can
either be press fit or welded into the vessel and placed at the
desired distance from the bottom surface 222 of the vessel so that
the outer edges of the diffuser element 232 is in contact with the
interior lateral walls of the vessel 212. The gap or spacing
between the bottom surface 222 of the vessel 212 and the diffuser
element 232 defines a plenum 226. Gas delivered into this plenum,
being confined by the edge of the diffuser plate in contact with
the walls, escapes mostly through the pores of the diffuser
plate.
The diffuser element 232 is made from a porous material. An example
of a porous material is a sintered frit. A sintered metal frit may
be used to make the diffuser element 232. An example of a suitable
sintered metal is stainless steel. Sintered stainless steel porous
frits are available from Mott Corporation, Farmington, Conn. In one
embodiment, the diffuser element is in the form of a disk having a
diameter of about 5.75 inches, a thickness of about 0.078 inches
and a pore size of about 40 microns. However, it will be understood
that the present invention is not limited to a diffuser element
having particular dimensions or pore size.
The diffuser element 232 is located in the lower portion of the
vessel and submerged in the liquid reactant 211. Gas inlet conduit
214 extends beneath the level of liquid reactant 211 and through
the diffuser element 232. Pressurized delivery of carrier gas 230
provides a mixture 32 of vaporized liquid precursor and carrier
gas, which then exits the vessel 212 through outlet conduit or port
216, which is connected to a CVD chamber 260. It will be
appreciated that one or more mass flow controllers or regulators
may be connected between the vessel 212 and CVD chamber 260, which
may be a conventional thermal or plasma-enhanced type. For example,
such a chamber 260 is described in the following commonly owned
issued U.S. Pat. No. 5,000,113, issued Mar. 19, 1991 to Adamik et
al.; U.S. Pat. No. 4,668,365, issued May 26, 1987 to Foster et al.;
U.S. Pat. No. 4,579,080, issued Apr. 1, 1986 to Benzing et al.;
U.S. Pat. No. 4,496,609, issued Jan. 29, 1985 to Benzing et al. and
U.S. Pat. No. 4,232,063, issued Nov. 4, 1980 to East et al., the
disclosures of which are incorporated by reference herein.
In use, the CVD apparatus described immediately above can be used
for the manufacture of films or layers on substrates, such as
semiconductor substrates. Thus a chemical vapor deposition method
includes flowing a carrier gas from a gas supply through the liquid
reactant 211 via inlet conduit or tube 214. The flow of carrier gas
through the liquid reactant causes the carrier gas and the liquid
reactant to flow through the porous member to create a vapor from
the liquid and transporting the vapor to a chamber under conditions
to convert the liquid reactant to form a layer on a substrate
contained within the chamber 260.
According to embodiments of the present invention, the use of a
porous member extending across the cross section of the vessel 212
results in negligible microdroplet formation and incorporation in
the mixed gas stream of carrier and liquid precursor vapor. This
also permits more effective consumption of the liquid reactant by
utilizing any remaining volume of the liquid precursor due to
displacement of the liquid by the fritted disk, and the liquid is
absorbed into the pores and microchannels of the porous member.
This porous member displaces liquid into a fixed 2 mm gap or plenum
between the bottom of the porous member and vessel or ampoule
bottom surface.
Although the invention herein has been described with reference to
particular embodiments, it is to be understood that these
embodiments are merely illustrative of the principles and
applications of the present invention. It will be apparent to those
skilled in the art that various modifications and variations can be
made to the method of the present invention without departing from
the spirit and scope of the invention. Thus, it is intended that
the present invention include modifications and variations that are
within the scope of the appended claims and their equivalents.
* * * * *